Magnetic-properties of two soils during reduction, drying and re-oxidation

Abstract

As part of a study of the use of magnetic properties to identify sources of sediments in water bodies for erosion studies, changes in the magnetic properties of two soils were determined during extended periods of reduction by saturation and during subsequent drying and oxidation. Mass magnetic properties rose during reduction and declined on re-oxidation. The results showed that a new magnetic compound was formed during reduction and then destroyed upon oxidation. These changes occurred in a soil which did not produce sulfides during reduction and the effects were little affected by amending the soil so that sulfides were formed. It was concluded that the compounds responsible for changes in magnetic properties were complex iron oxides rather than sulfides. Differences between the magnetic properties of wet and air dried samples were considered to be mainly due to physical rather than chemical changes. Therefore, when using magnetic properties as a tool for the identification of sediment sources, diagenesis and the effects of drying need to be taken into account.